This paper presents integrated Geographic Information Systems (GIS) developed to perform seismic hazard and risk assessment. The systems can perform complex interactive computations which would be difficult and time-consuming to carry out manually, such as: (i) deterministic and probabilistic earthquake hazard analysis; (ii) evaluation of different ground motion and seismic source models; (iii) assessment of the effect of local geology; (iv) generation of design-compatible time histories; and (v) damage assessment of spatially distributed structural systems. An application for the New York City metropolitan area demonstrates that despite the scarcity of recorded data, incomplete knowledge of seismic wave propagation characteristics, and sometimes insufficient geologic data, it is possible to arrive at a rational estimate of the seismic risk potential in a probabilistic manner, combining available information and uncertainties in the GIS environment.